1. Field of the Invention
The invention relates to containers for pressurized gas, which each has a valve for filling and emptying and safety relief means, such as, a frangible safety relief device.
2. Prior Art
Containers for pressurized gas have long had safety relief means in order that the pressure in the container not become so great (say, during filling) as to present a problem of the tank exploding. A typical safety relief means is a frangible safety relief device located in a port in the container. The safety relief device is welded around its perimeter to the tank. The cup-shaped relief means typically has a hemispherical bottom protruding into the cup. When the pressure in the tank exceeds a predetermined level such as when someone filling the tank tries deliberately to or inadvertently places too much gas into the tank, the hemispherical portion of the frangible cup-sahped safety means ruptures. The result is that the gas escapes from the container through the rupture at a very rapid velocity. The result sometimes injures the person filling or using the tank by the high velocity escaping gas, hitting them in the face or upper torso. Usually the safety release means is located in the top portion of the pressurized gas container in close proximity to the valve used for filling and emptying the container. The location of the safety relief device near the valve makes it all the more dangerous when the safety relief device ruptures to relieve gas pressure in the container since that means that the direction of the escaping gas is upwards. Also, sometimes the pressure may cause the weld seal around the perimeter of the safety relief device to totally break, hurling the separated relief device itself upwards at the person.
While the frangible safety relief device is an important safety feature, its very mechanism sometimes causes a safety problem to those who use and fill such containers. The art has recognized the need to solve the safety problem present by the frangible safety cup means, but has been unable to provide a simple, effective and inexpensive solution thereto.